Manage load shedding

**Justloadit** · 24-Feb-15, 04:47 PM

There is a start up current which is extremely difficult to measure, unless you have a peak detector instrument.
This peak current draw plays havoc with inverters, which can only take an overload for a cycle or two, then shut down with an overload. So effectively get an inverter which is double the size of what you are using as a starting point. The addition of batteries does not influence the inverter, but rather the charging process.

**AndyD** · 24-Feb-15, 11:24 PM

If the inverter is seamless (10 mS) when power fails I would normally spec a safety margin of 20-25% because PC's and other devices which would include motors if you have them won't restart, they'll carry on running without interruption. If you already have any small UPS's at your PC's or other equipment I'd take your consumption readings with these out of circuit because they'll be redundant if you're installing an inverter or large UPS for everything. Removing the small UPS's might drop your load requirement by up to 20%. If you're thinking of a generator then leave them in circuit because you're going to need them to carry the load whilst the genny is started.

Overload handling ability varies massively between different inverters, the unit I installed at home which I showed in another thread will tolerate a 50% overload for 5 seconds and a 20% overload for 15 seconds which would be more than sufficient for most applications. We've installed other inverters for customers such as the Victronics units which can take a 100% overload for short durations and a 50% overload for around a minute but this kind of over-specification is reflected in the price you pay for them.

**wynn** · 25-Feb-15, 09:08 AM

Originally Posted by AndyD

are you sure they're not just trying to palm off any 'fit for purpose' responsibility they may have had under their contract or service level agreement by making it your problem to install an extra back-up solution for their equipment?

I would think they are trying to sell a bigger system!

**IanF** · 25-Feb-15, 10:42 AM

Thanks for the info Andy, I am busy measuring again. The wide format printer max watts cam down from 120w to 96w so that is a big difference. Just need to round up some kettle cords.

**bones** · 23-Mar-15, 02:30 PM

going to do this for my laptops Ian have a look
cost is not to high so worth giving it a go

This for more lcd displays for laptop USB to VGA adapter

usb3 with power

Ideal for use with today’s Ultrabooks and thin-and-light laptops, Transcend’s SuperSpeed USB 3.0 Hub transforms a single USB 3.0 port into four, instantly expanding the number of high-performance USB 3.0 devices you can connect to your computer at the same time. With the included power adapter, the Hub3 can supply high output currents of up to 2A via its dedicated fast charging port. This allows the Apple iPad and other portable devices with demanding power requirements to charge much quicker than using a standard USB port.

**bones** · 23-Mar-15, 02:32 PM

Ian do you have a laser cutter
how do you keep the thing
from crashing?

**IanF** · 23-Mar-15, 04:28 PM

Hi Bones,
That USB adapter looks good so you can use it on the desktop as well. I will look at that later.
For the laser cutter it is a chinese one and one thing is when the power goes it just stops. Then when the power comes back you just switch it back on and it restarts in exactly the same place and finishes the job. Then we also bought a voltage regulator for the laser and it just runs no hassle and the current tube has been going for 2 years.

**bones** · 23-Mar-15, 09:20 PM

Originally Posted by IanF

Hi Bones,
That USB adapter looks good so you can use it on the desktop as well. I will look at that later.
For the laser cutter it is a chinese one and one thing is when the power goes it just stops. Then when the power comes back you just switch it back on and it restarts in exactly the same place and finishes the job. Then we also bought a voltage regulator for the laser and it just runs no hassle and the current tube has been going for 2 years.

mine was secondhand to start with
then got in the way of some vandals
got it working but it freezes a lot

power dip finally put it out of my
misery at 3:20 pm today i am looking
for one now any suggestions?

got a tight budget for something
basic

**bones** · 23-Mar-15, 09:26 PM

i saw one for about R51k not
bad looking systems

http://am.co.za/laser

**IanF** · 24-Mar-15, 08:39 AM

Bones, I have an aversion to software dongles but would go and have a demo on that machine as it is a good price. I got my machine from astroware and here is a link to a similar one. Then also get some thing to control the power spikes.
I got my last tube from perfect laser but haven't had to replace yet. They also sell machines.